A typical radio transceiver comprises an antenna, a signal processing unit for baseband processing of received signals and signals that are to be transmitted. Between the antenna and the signal processing unit are a receive chain and a transmit chain. The receive chain converts received radio frequency (RF) signals down to baseband for further processing by the signal processing unit. The transmit chain generally converts signals from baseband to RF for transmission from the antenna. The receive chain can comprise a low noise amplifier (LNA) which amplifies the received signal, one or more mixers which mixes the amplified signals with signals from local oscillators (LOs) to convert to Intermediate frequency (IF). The analogue IF signals may then converted to digital signals using analogue-to-digital converters (ADCs). The digital signals from the ADCs may then be passed further down the receive chain for further processing.
In many applications it would be desirable, in order to reduce size and cost, to implement the entire transceiver, on a single integrated circuit (IC). One difficulty in designing such an IC is that the manufacturing tolerances of devices tend to increase with decreasing feature sizes. This can lead to devices, which are intended to be identical, having different properties and characteristics. This leads to added difficulty in controlling the required performance of the components of the transceiver. Additionally, there is increasing market demand for lower power products.
There is therefore a need for greater control of transceiver component performance whilst utilising a small on-chip area and low power.